/*
    * Copyright 2011 Jakub Narloch
    *
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    * http://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.exolab.castor.xml;
  
  import java.util.ArrayList;
  import java.util.Enumeration;
  import java.util.List;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.xml.sax.helpers.AttributeListImpl;
  
  /**
   * This class is an actual namespace stack implementation, responsible for
   * adding and removing namespace scopes, as well as resolving namespace urls and
   * prefixes by traversing all the namespace stack.
   * 
   * @author <a href="mailto:jmnarloch AT gmail DOT com">Jakub Narloch</a>
   * @since 1.3.3
   */
  @SuppressWarnings("deprecation")
  public class NamespacesStack {
  
     private final Log logger = LogFactory.getLog(this.getClass());
     
     /**
      * Represents the string used for indicating default namespace, by default
      * empty string is used.
      */
     private static final String DEFAULT_NAMESPACE = "";
  
     /**
      * Represents a stack of namespaces.
      */
     private List<Namespaces> namespaceStack = new ArrayList<Namespaces>();
  
     /**
      * Adds a namespace to current scope.
      * 
      * @param namespacePrefix
      *           the namespace prefix
      * @param namespaceUri
      *           the namespace uri
      */
     public void addNamespace(String namespacePrefix, String namespaceUri) {
        Namespaces namespaces = getCurrentNamespaceScope();
        if (namespaces != null) {
           namespaces.addNamespace(namespacePrefix, namespaceUri);
        }
     }
  
     /**
      * Adds the default namespace to current scope.
      * 
      * @param namespaceUri
      *           the namespace uri
      */
     public void addDefaultNamespace(String namespaceUri) {
        addNamespace(DEFAULT_NAMESPACE, namespaceUri);
     }
  
     /**
      * Removes the namespace from current scope using the namespace prefix
      * 
      * @param namespacePrefix
      *           the prefix of the namespace to remove
      */
     public void removeNamespace(String namespacePrefix) {
        getCurrentNamespaceScope().removeNamespace(namespacePrefix);
     }
  
     /**
      * Retrieves the namespace uri bound to specified prefix.
      * 
      * @param namespacePrefix
      *           the namespace prefix
      * 
      * @return the namespace uri bound to the prefix, or null if no namespace has
      *         been bound for the given prefix
      */
     public String getNamespaceURI(String namespacePrefix) {
        String namespaceUri = null;
        for (int ind = namespaceStack.size() - 1; ind >= 0 && namespaceUri == null; ind--) {
           namespaceUri = namespaceStack.get(ind).getNamespaceURI(namespacePrefix);
        }
        return namespaceUri;
    }
 
    /**
     * Declares the namespaces using the attribute list.
     * 
     * @param attributeList
     *           the list of attributes containing the namespaces
     * @param localOnly
     *           whether the namespaces will only registered in current namespace
     *           context or in entire stack
     */
    @SuppressWarnings("deprecation")
    public void declareAsAttributes(AttributeListImpl attributeList, boolean localOnly) {
       getCurrentNamespaceScope().declareAsAttributes(attributeList);
       if (!localOnly) {
          for (int ind = namespaceStack.size() - 1; ind >= 0; ind--) {
 
             namespaceStack.get(ind).declareAsAttributes(attributeList);
          }
       }
    }
 
    /**
     * Retrieves the default namespace namespace uri.
     * 
     * @return the default namespace uri
     */
    public String getDefaultNamespaceURI() {
       return getNamespaceURI(DEFAULT_NAMESPACE);
    }
 
    /**
     * Retrieves the namespace prefix for the given namespace uri.
     * 
     * @param namespaceUri
     *           the namespace uri
     * 
     * @return the
     */
    public String getNamespacePrefix(String namespaceUri) {
       String namespacePrefix = null;
       for (int ind = namespaceStack.size() - 1; ind >= 0 && namespacePrefix == null; ind--) {
          namespacePrefix = namespaceStack.get(ind).getNamespacePrefix(namespaceUri);
       }
       return namespacePrefix;
    }
 
    /**
     * Retrieves the non default namespace prefix for the given namespace uri.
     * 
     * @param namespaceUri
     *           the namespace uri
     * 
     * @return the
     */
    public String getNonDefaultNamespacePrefix(String namespaceUri) {
       String namespacePrefix = null;
       for (int ind = namespaceStack.size() - 1; ind >= 0 && namespacePrefix == null; ind--) {
          namespacePrefix = namespaceStack.get(ind).getNonDefaultNamespacePrefix(namespaceUri);
       }
       return namespacePrefix;
    }
 
    /**
     * Retrieves the namespace prefixes registered in current scope.
     * 
     * @return the enumeration of namespace prefixes
     */
    public Enumeration<String> getLocalNamespacePrefixes() {
       Namespaces namespaces = getCurrentNamespaceScope();
       return namespaces != null ? namespaces.getLocalNamespacePrefixes() : null;
    }
 
    /**
     * Adds a new namespace scope.
     */
    public void addNewNamespaceScope() {
       namespaceStack.add(new Namespaces());
    }
 
    /**
     * Removes the namespace scope.
     */
    public void removeNamespaceScope() {
       // removes the current namespace
       if (namespaceStack.size() > 0) {
          namespaceStack.remove(namespaceStack.size() - 1);
       } else {
          this.logger.error("Trying to remove a namespaces scope from an empty stack of Namespaces");
       }
    }
 
    /**
     * Retrieves the current namespace scope.
     * 
     * @return the current namespace scope.
     */
    public Namespaces getCurrentNamespaceScope() {
       if (namespaceStack.size() == 0) {
          addNewNamespaceScope();
       }
       return namespaceStack.get(namespaceStack.size() - 1);
    }
 }